San Francisco on Thursday became the only government entity in the United States to grant marriage licenses to same-sex couples. City officials followed a directive set in motion by Mayor Gavin Newsom. By the end of Thursday, 15 same-sex couples had been wed.

Longtime lesbian activists Phyllis Lyon, 79, and Del Martin, 83, were married just before noon by city assessor Mabel Teng in a closed-door civil ceremony at City Hall, mayor's spokesman Peter Ragone said. The two have been a couple for 51 years. Martin and Lyon met in Seattle in 1950 and began dating in 1952. They moved to San Francisco in 1953. The two women founded the Daughters of Bilitis, the first national lesbian rights organization. "Phyllis and I demonstrated our commitment to one another more than half a century ago," said Martin. "Today San Francisco has demonstrated its commitment to us through equality and fairness."

It remains unclear what practical value their marriage license will have, but the symbolism was self-evident on a day when lawmakers in Massachusetts were debating a constitutional amendment that would ban gay marriage. The couple said they were going home to rest and didn't plan anything to celebrate. Still, it was a profound moment for the pair, veterans of decades of gay rights struggles.

Thursday's marriage defies a ballot measure California voters approved in 2000 that defined marriage as a union between a man and a woman. State lawmakers subsequently passed a domestic-partnership law that, when it goes into effect in 2005, will offer the most generous protections to gays and lesbians outside Vermont. The couple seemed proud of their efforts to set another precedent with their marriage. "Why shouldn't we be able to marry?" Lyon asked.

Ragone said that Thursday afternoon, officials would begin issuing a marriage license to any gay or lesbian couple who requested one. One couple was already stationed outside City Hall, one of the women wearing a white wedding dress. Newsom was not present at the morning ceremony. The two official witnesses were Kate Kendell, director of the National Center for Lesbian Rights, and former city official Roberta Achtenberg.

California's domestic-partnership law--signed in September by then-governor Gray Davis--that expands the rights of gay couples in areas including health coverage, parental status, property ownership, and funeral arrangements. It gives both partners equal status as parents if they have or adopt a child together and allows them to seek child support and alimony. There are 8,902 same-sex couples living in the same household in San Francisco, according to the 2000 U.S. Census.

"For many Americans, their wedding day is one of the happiest days of their life," said Geoffrey Kors, executive director of Equality California. "For these San Francisco couples, it is no different, with one exception. Yesterday they couldn't get married. Today they can. To suggest that these couples are experiencing a profound sense of happiness is an understatement."

Dorothy Ehrlich, executive director of the American Civil Liberties Union of Northern California, added, "Just as we told the state in 1974, when they passed a statute limiting marriage to a man and a woman, that kind of discrimination against same-sex couples violates the California constitution's promise of equality. Discrimination in marriage was wrong then, and it's wrong now."

Gary Buseck, legal director at Lambda Legal Defense and Education Fund, said, "We've waited a long time to see a gay couple get married. This isn't a game; it's about real people's lives. Lesbian and gay couples badly need the protections that only marriage can provide. Today there are married same-sex couples in San Francisco who can show the rest of the state and the country that nobody else's marriage is weakened when all couples have access to these critical protections. If antigay groups take the government to court tomorrow or in the days ahead, we intend to take any legal action necessary to make sure marriage licenses continue to be issued."